Decomposition of NO3- by lead pellets with wet ball milling

Citation
M. Uchida et al., Decomposition of NO3- by lead pellets with wet ball milling, WASTE MAN, 19(3), 1999, pp. 213-219
Citations number
7
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environmental Engineering & Energy
Journal title
WASTE MANAGEMENT
ISSN journal
0956-053X → ACNP
Volume
19
Issue
3
Year of publication
1999
Pages
213 - 219
Database
ISI
SICI code
0956-053X(1999)19:3<213:DONBLP>2.0.ZU;2-E
Abstract
The reduction of an ammonium nitrate solution by lead pellets during wet ba ll milling was studied, as a method of removing concentrated NO3- from wast ewater. Metal oxides forming on the surface of lead pellets in a ball mill reactor are continuously removed by contact between the pellets. At tempera tures between 25 and 80 degrees C and a ball mill rotation speed, omega, of 80-180 rpm, initial concentrations of NH4NO3 between 0.05 and 0.1 M, NO3- rapidly reduce to NO2-, and then to N-2 and NH3. Depending on the pH of the solution, the precipitation of basic lead (II) nitrate and basic lead (II) nitrite occurs simultaneously with the reduction of NO3- and NO2-. As the temperature increases, the rate of reduction of NO3- increases and the prop ortion of NH3 formed increases, as that of N-2 decreases. The rate of reduc tion of NO3- is governed by the rate of wear of the outer layer of the Pb p ellets, which is determined by the speed of rotation of the ball mill. In t his system, there are three competitive reactions: the reduction of NO3- an d NO2- by Pb, the reduction of NO2- by NH4+ and the precipitation of basic lead (II) salts. (C) 1999 Elsevier Science Ltd. All rights reserved.